That's a good point, but if you find yourself doing more and more Mac-related stuff, the MBP can do a great job for you. You can use any Win programs in XP via Boot Camp and with an external drive handy, you can store pictures off the internal drive and save that space for needed software.

If you get an inexpensive pc, realize that it's going to come with Vista and without upgrading it and making it more expensive, Vista's going to bog it down a bit.